This invention relates to roll baling machines which form cylindrical rolls of crop material and which are commonly referred to as round balers.
In U.S. Pat. No. 4,566,379, there is disclosed a round baler having two sets of bale-forming means which define a bale-forming chamber which is expandable from a small start chamber to a full size chamber. In order to provide the expandable bale-forming chamber, one set of bale-forming means is movable with respect to the other set but it has been found that with some crops and/or crop conditions, this is insufficient to ensure that the core of a bale being formed is properly constituted and that the bale is continually rotated during formation. It is highly desirable that the core of a bale being formed has the correct density. It is furthermore essential to ensure that a bale being formed undergoes continual rotation in order that crop material being fed into the machine is taken in and added to the bale. If bale rotation ceases, then further crop material cannot be added to the bale which thus results in the baler becoming blocked.
It is an object of the present invention to overcome the shortcomings of this known machine while taking advantage of the basically satisfactory general tvoe of bale-forming means employed therein.